Project Summary/Abstract Strategies to promote wound healing and support engraftment of cell transplants may ultimately lead to effective treatments for many degenerative diseases. Yet, to date control over insufficient or pathologic revascularization of transplants, damaging inflammation, and/or dysregulated tissue differentiation remains difficult to achieve solely by pharmacologic treatments. The transplant microenvironment by its own imparts many constrains, i.e. cell transplants may need to adapt to sites of implantation that not always recapitulate the cellular composition, molecular and/or physical properties of the organ of origin, all factors impacting on grafts long-term survival and function. The rapid progress in tissue engineering technologies capable of reconstituting structural and molecular cues mimicking native tissue microenvironments offers new opportunities to overcome these limitations. In this multi-investigator project, we integrate complementary areas of expertise on vascular biology, cellular immunology, pancreatic tissue and stem cell biology, as well as bioengineering of novel biomaterials to address a) pro-repair functions of novel biochemical cues (Slit-2 and Netrins) that we have identified in the developing pancreas as critical regulators of endocrine differentiation and modulators of vasculogenic/immune activities, and b) the functional impact of recapitulating in injury settings mechanical cues that we have measured in the developing and adult human pancreas. To implement these studies we will adopt an innovative bioengineering approach that allow for spatial patterning and temporal modulation of Slit and Netrin proteins in vascular networks and extra-vascular spaces, as well as for pharmacologic control of tissue stiffness. Based on preliminary studies supporting feasibility, we plan to dissect repair mechanisms dependent on these biochemical and physical cues, and ultimately their impact on endocrine responses to metabolic changes as read-out of grafts function. We will focus on the following aims: Aim 1: To investigate the impact of Slit-2 engineered in PEG-based scaffolds on the revascularization and immunomodulation of tissue grafts. Aim 2: To assess the effects of Netrin-functionalized scaffolds on the differentiation and function of immature tissue progenitors. Aim 3: To address the impact of tuning the mechanical properties of support scaffolds on tissue progenitors growth, differentiation and functional maturation. Collectively, results from this collaborative project will establish the ground-work for the development and production of a new generation of clinically-relevant scaffolds that will be relevant to a wide range of medical conditions requiring cell replacement therapies and/or tissue regeneration.